Relative Risks of Cardiopulmonary and Lung Cancer Mortality by PM2.5 Exposure in Ambient Air of Delhi Particularly During Smog Episode

ABSTRACT Background Delhi, the capital city of India has experienced the problem of the great smog during November since a long time. Adverse meteorological conditions, stubble burning, and the celebration of Diwali were considered as the major responsible factors for the smog episodes. This study was designed to identify the concentration and relative risks associated with the exposure of PM2.5 in ambient air of Delhi during the episodic events. Methods 24-h average ambient levels of PM2.5 were procured for the year 2015–2020. Relative risks of cardiopulmonary and lung cancer diseases associated with PM2.5 exposure have been estimated using a probabilistic approach of risk assessment. Findings The average relative risks (2015–2020) for lung cancer mortality (RR 2.15; 95% CI 2.13, 2.17., p < 0.001) were observed higher than cardiopulmonary mortality (RR 1.66; 95% CI 1.65, 1.67., p < 0.001). An attempt has been done to identify the effect of high exposure concentration on relative risks particularly during smog period. The estimated relative risks during November (2016–2018) for lung cancer mortality were ranged as 2.51–2.68 and cardiopulmonary mortality were ranged as 1.85–1.93. Conclusion Such high levels of associated relative risks during such episodes could be considered as an important additive hazard factor for overall mortality burden. Graphical Abstract Highlights PM2.5 produced during smog event has a serious impact on the respiratory and cardiopulmonary health, resulted in increment of relative risks; Relative risks of lung cancer mortality were higher in compare of cardiopulmonary mortality, suggesting more carcinogenic effects of fine particles on human health; The results of the study suggest that there is a strong effect of location, days and burning practices, when estimating air quality.